Synthesis of linear primary alcohols from internal olefins

ABSTRACT

It has been discovered that heating C4-C17 internal olefins to 300* to 500*F under pressures of 1000 to 3500 psig for 1 to 20 hours with an oxo catalyst prior to contacting with hydrogen results in a higher selectivity to primary alcohols than does the conventional hydroformylation procedure of heating all the reactants together.

United States Patent [1 1 Macaluso, Sr. et al.

[ Sept. 23, 1975 SYNTHESIS OF LINEAR PRIMARY ALCOHOLS FROM INTERNAL OLEFINS [75] Inventors: Anthony Macaluso, Sr., Port Arthur; Orville W. Rigdon, Grooves, both of Tex.

[73] Assignee: Texaco Inc., New York, NY.

[22] Filed: Jan. 8, 1973 [21] Appl. No.: 322,055

[52] US. Cl 260/632 HF; 260/683.2 [51] Int. Cl. C07C 29/16 [58] Field of Search 260/632 HF, 683.2

[56] References Cited UNITED STATES PATENTS 3,139,460 6/1964 Eisenmann 260/683.2

3,239,569 3/1966 Slaugh et a1. 260/632 HF 3,432,570 3/1969 Hoffman et al.... 3,542,896 11/1970 Butte 260/683.2

Primary Examiner.loseph E. Evans Attorney, Agent, or FirmT. l-l. Whaley; C. G. Ries; Henry W. Archer [57] ABSTRACT 7 Claims, N0 Drawings SYNTHESIS OF LINEAR IRIMARY ALCOHOLS FROM INTERNAL OLEFINS BACKGROUND OF THE INVENTION This invention is concerned with the preparation of 5 linear primary alcohols from. predominantly internal olefins. i

The oxo or hydroformylation -reaction is an'important commercial method for the preparation of aldehydes and/or alcohols from olefins which may be shown in the general case by the following'equation:

' ANALYSIS'OF THEPRIOR ART 0 ll C-H linear alcohol branched alcohol biodegradability is inversely proportional to the amount of branched isomer present in thefinal alcohol product. Hence, there is considerable interest in limiting the amount of branched isomer.

SUMMARY OF THE INVENTION This invention relates to a procedure'for the preparation of primary alcohols from predominantly internal 40 olefins having the double bond'randomly distributed along the carbon chain wherein the alcohols (Cg-C contain more linear isomer (as highas 7'6percent) than those from conventional procedures. In this procedure the internal olefins are contacted with the' cobalt source (usually cobalt acetate) and a ligand (usually tri-n-butylphosphine) in the absence of carbon monoxide and hydrogen (synthesis gas) or in the presence of carbon monoxide but without hydrogen. The reaction mixture is heated to the reaction temperature and then the synthesis gas or hydrogen (when carbon'monoxide is added initially) is added to the desired pressure. This procedure gives the olefins an opportunity to isomerize to the more desirable alpha structure before being con-' verted to alcohols. I The internal olefins such as dehydrogenated normal paraffins which contain about 10 volume of internal olefins can be charged alone or in the presence of inert solvents. A hydrogenzcarbon monoxide ratio from 1:1

to 3:1 (preferably 2:1) can be used. The cobalt source can be dicobalt octacarbonyl, the cobalt salt "of an organic acid (preferably cobalt acetate); cobalt adsorbed on a support or cobalt itself. The ligand can be any tertiary organophosphine (preferably tri-n' butylphosphine). Reaction temperatures from 300F to' 500F (preferably from 340F to400F reaction pressures from 1000 to 3500 psig (preferably from 1500 to V 2500 psig) and reaction times from 1 to 20 hours (preferably 3 to 10 hours) ca'n be employed.

ligands is much more effective in reducing branched isomers in the hydroformylation of land 2-olefins than the conventional oxo catalyst system (l-lCo(- (50);). a

It has also been observed by'other researchers that the percent of linear isomers decreased as the chain length of the olefin was increased. Therefore, even though some remarkably high linear/branched product ratios are reported in the literature, thecharge is usually a C5, to C5 olefin (usuallypropylene). The carbon distribution of the internal olefins present in our dehydrogenated normal paraffin charge is in the C -C range, thereby making the predominance of linear products difficult. i r

A previous experimental procedure for the preparation of alcohols from landZ-hexehe is reported in the literature'(A. Hershman and J. H. Craddock, I&EC ProductResearch andmDevelopment, Vol. 7, No. 3, page 227 11968. According to this reference the catalyst solution is placedin an autoclave and heated to the desired temperature under a synthesis gas pressure of to 200 psig. The liquid olefin (usually alpha olefins) is then injected and the reactor is pressuredto the desired pressure. This procedure differs from the instantinvention in that the liquid olefin is charged after reaction temperature is reached. Here the internal olefins, the cobalt source and the ligand are initially charged to the reactor. The reaction mixture is then heated to the desired temperature. Another difference in the instant procedure compared to the literature reference mentioned above is that here the reaction mixture is heated to the desired temperature either without the synthesis gas or with carbon monoxide alone, whereas in the published procedure the synthesis gas (carbon monoxide and hydrogen) is charged to the reactor before heating up to the desired temperature.

The marked advantage of the present procedure over a conventional reaction procedure bf charging the catalyst solution and internal olefins to the reactor, pres surihg'ithereaetpr to the desired initial pressure with synthes s asfandi heating the mixtureto the reaction temperature; isthat higher yields of the commercially desired linea'r products "are obtained. The linear/- branched product ratios obtained from our novel procedure are comparable to those obtained for hydroformylation reactions starting with alpha olefins in the same carbon number range as shown in Example 7 below.

DESCRIPTION OF PREFERRED EMBODIMENTS EXAMPLE 1 Cobalt acetate tetrahydrate (4.9 g., 0.02 mols of cobalt) tri-n-butylphosphine (8.0 g., 0.04 mols and the olefin-paraffin mixture containing about volume percent olefins C -C (400 g., 0.26 mols of olefin) were added to alOOO ml stainless steel autoclave and the reactor was flushed with nitrogen and then heated with rocking to the reaction temperature (340F). The reaction mixture was kept at this temperature for minutes. The reactor was then pressured to 2200 psig with synthesis gas (hydrogenzcarbon monoxide molar ratio of 2). The reaction was allowed to continue until no further up-take of the synthesis gas was observed. At the end of this time (140 minutes), the autoclave was cooled, vented and emptied. The crude reaction effluent was decobalted with several successive portions of a 10 percent aqueous acetic acid solution. The decobalted reaction effluent was then vacuum fractionated to remove light materials, unreacted olefins and mixed paraffins. The product alcohols were then taken overhead in 76 mols percent selectivity* and contained 63 percent of the linear isomer. Olefin conversion was calculated as 72 wt. percent. Selectivity to alcohols. mol.% lOO/Mols of Olefin Reacted EXAMPLE 2 Cobalt acetate tetrahydrate (4.9 g., 0.02 mols of cobalt), tri-n-butylphosphine (8.0 g., 0.04 mols) and the olefin-paraffin mixture containing about 10 volume percent olefins C, C, (400 g., 0.26 mols of olefin) were added to the 1000 ml stainless steel autoclave, and the reactor was flushed with nitrogen and then heated with rocking to the reaction temperature (340F). When the reaction temperature was reached, the reaction mixture was kept at this temperature for 15 minutes. After this 15 minute holding period, the reactor was pressured to 2200 psig with synthesis gas (hydrogenzcarbon monoxide molar ratio of 2). The reaction was allowed to continue until no further up-take of the synthesis gas was observed. At the end of this time (185 minutes), the autoclave was cooled, vented and emptied. The crude reaction effluent was decobalted with several successive portions of a 10 percent aque-. ous acetic acid solution. The decobalted reaction effluent was then vacuum fractionated to remove light materials, unreacted olefins and mixed paraffins. The product alcohols were then taken overhead in 60 mol percent selectivity and contained 68 percent of the linear isomer. Olefin conversion was calculated as 63 wt. percent.

Mols of Alcohol Produced X EXAMPLE 3 Cobalt acetate tetrahydrate (4.9 g., 0.02 mols of cobalt), tri-n-butylphosphine (8.0 g., 0.04 mols) and the olefin-paraffin mixture containing about 10 volume percent olefins C -C (400 g., 0.26 mols ofolefin) were added to the 1000 ml stainless steel autoclave and the reactor flushed with nitrogen and then heated with. rocking to the reactor temperature (340F). When the reaction temperature was reached, the reaction mixture was kept at this temperature for 15 minutes'After this 15 minute holding period, the reactor was pressured to 2200 psig with synthesis gas (hydrogenzcarbon monoxide molar ratio of 2). The reaction was allowed to continue until no further up-take of the synthesis gas was observed. At the end of this time (287 minutes), the autoclave was cooled, vented and emptied. The crude reaction effluent was vacuum fractionated to remove light materials and unreacted olefins and mixed paraffins. The bottoms from the distillation, which contained the product alcohols, were decobalted with several successive portions of an aqueous 10 percent acetic acid solution. The product alcohols were collected in 65 mol percent selectivity and contained 76 percent of the linear isomer. Olefin conversion was calculated at weight percent.

COMPARATIVE EXAMPLES The following examples show results obtained using conventional procedures or, in the case of Example 7, alpha olefins as charge stock.

EXAMPLE 4 Cobalt acetate tetrahydrate (4.9 g., 0.02 mols of cobalt), tri-n-butylphosphine 8.0 g., 0.04 mols) and the olefin-paraffin mixture containing about 10 volume percent olefins C -C (400 g., 0.26 mols of olefin) were added to the 1000 ml stainless steel autoclave and the reactor was flushed with synthesis gas (hydrogen:- carbon monoxide molor ratio of 2), pressured to 1700 psig and heated to the reaction temperature (340F). The reaction was allowed to continue until no further up-take of the synthesis gas was observed. At the end of this time (73 minutes), the autoclave was cooled, vented and emptied. The crude reaction effluent was stirred and refluxed with several successive portions of an aqueous 10 percent acetic; acid solution to decompose the cobalt carbonyls and remove the cobalt from the organic medium as a water soluble salt. The decobalted reaction effluent was then vacuum fractionated to remove light materials, unreacted olefins and mixed paraffins. The product alcohols were then taken overhead in 73 mol percent selectivity and contained 52 percent of the linear isomer. Olefin conversion was calculated as 72 wt. percent.

EXAMPLE 5 Cobalt acetate tetrahydrate (4.9 g., 0.02 mols of cobalt), tri-n-butylphosphine (8.0., 0.04 mols), stearic acid (1 1.4 g., 0.040 mols) and the olefin-paraffin mixture vcontaining about l0 volume. percent olefins C -C (400 g.,-0.26 mols of olefin) were added to the 1000 ml stainless steel autoclave and. the reactor was flushed with synthesis gas (hydrogemcarbon monoxide molar ratio of 2), pressured to i700 psig and heated to the reaction temperature (340F). The reaction was allowed to continue until no further up-take of the synthesis gas was observed. At the end of this time (60 minutes), the autoclave was cooled, vented and emptied. Thecrude reaction effluent was decobalted with several successive portions of an aqueous 10 percent acetic acid solution. The decobalted reaction effluent selectivity and contained 47 percent of the linear isomer. Olefin conversion was calculated as 84 wt. percent.

A second run conducted under the same reaction conditions and charge stock quantities as above yielded product alcohols in 83 mol percent selectivity. The product alcohols contained 55 percent of the linear isomer. Olefin conversion was calculated as 85 wt. percent.

:EXAMPLE 6 Cobalt stearate (2.3 g., 0.004 mols of cobalt), tri-nbutylphosphine (0.8 g., 0.004 mols) and the olefinparaffin mixture containing about 10 volume percent olefins C -C (400 g., 0.26 mols of olefin) were added to the 1000 ml stainless steel autoclave and the reactor was flushed with synthesis gas (hydrogemcarbon monoxide ratio of 2), pressured to 1700 psig and heated to the reactor temperature (340F). The reaction was allowed to continue until no further up-take of the synthesis gas was observed. At the end of this time (45 minutes), the autoclave was cooled, vented and emptied. The crude reaction effluent was decobalted with several successive portions of an aqueous 10 percent acetic acid solution. The decobalted reaction effluent was then vacuum fractionated to remove light materials, unreacted olefins and mixed paraffins. The product alcohols were then taken overhead in 32 mol percent selectivity and contained 44 percent of the linear isomer. Olefin conversion was calculated as 85 wt. percent.

EXAMPLE 7 Dicobalt octacarbonyl (5.3 g., 0.031 mols of cobalt), tri-n-butylphosphine (6.2 g., 0.031 mols), stearic acid (17.8 g., 0.063 mols) and C, C alpha olefins (172.8 g., 1.0 mols) were added to the 1000 ml stainless steel autoclave and the reactor was purged with synthesis gas (H zCo mol ratio, 2: l and then pressured to 1300 psig with the synthesis gas (H :CO mol ratio, 2:1 The reaction mixture was heated with rocking to the reaction temperature (383F). The reaction was allowed to continue until no further up-take of the synthesis gas was observed. At the end of this time (180 minutes), the autoclave was cooled, vented and emptied. The crude reaction effluent was decobalted with several successive portions of a 10 percent aqueous acetic acid solution. The decobalted reaction effluent was then vacuum fractionated to remove light materials. The product alcohols were then taken overhead in 86 mol percent selectivity and contained 74 percent of the linear isomer. Olefin conversion was calculated as 82 wt. percent.

The important fact to observe in comparing the data of Examples l-3 with those of Examples 4-6 is that the former gave as high as 76 percent linear isomers while the conventional procedure of Examples 4-6 gave only from 44 to 55 percent. These results compare favorably with that of Example 7 where starting with an alpha olefin charge the product alcohols contained 74 percent of the linear isomer. Thus the results of Examples l-3 point out the unobvious nature of the present invention.

Similarly hydroformylated with good results were C -C C -C and C C olefinic fractions so that the process of the invention can be said to apply generally to predominantly internal olefins having from 4 to 17 carbon atoms per molecule.

What is claimed is:

l. A two step process for the conversion of a feed charge consisting of predominantly internal olefins having from 4 to 17 carbon atoms per molecule to the corresponding linear alcohols having one more carbon atom to the molecule than said olefins which comprises heating said charge with a cobalt salt of an organic acid and a ligand consisting of a tertiary organophosphine at a reaction temperature of from about 300F to about 500F in the absence of carbon monoxide and hydrogen or in the presence of carbon monoxide but without hydrogen thereby isomerizing said olefins to their alpha structure; maintaining the reaction mixture at said temperature for about 15 minutes; then hydroformylating said alpha olefins by contacting said reaction mixture containing said alpha olefins with synthesis gas under a pressure of from about 1000 to 3500 psig for a reaction time of from about 1 to 20 hours and recovering predominantly linear primary alcohols.

2. The process of claim 1 wherein the isomerizing reaction pressure ranges from 1500 to 2500 psig.

3. The process of claim 1 wherein the hydroformylation reaction time ranges from 3 to 10 hours.

4. The process of claim 1 wherein said olefins are present in a charge of dehydrogenated normal paraffins.

5. The process of claim 1 wherein said catalyst is cobalt acetate.

6. The process of claim 1 wherein said ligand is tri-nbutylphosphine.

7. The process of claim 1 wherein isomerizing is carried out at 340 to 400F. 

1. A TWO STEP PROCESS FOR THE CONVERSION OF A FEED CHARGE CONSISTING OF PREDOMINANTY INTERNAL OLEFINS HAVING FROM 4 TO 17 CARBON ATOMS PER MOLECULE TO THE CORRESPONDING LINEAR ALCOHOLS HAVING ONE MORE CARBON ATOM TO THE MOLECULE THAN SAID OLEFINS WHICH COMPRISES HEATING SAID CHARGE WITH A COBALT SALT OF AN ORGANIC ACID AND A LIGAND CONSISTING OF A TERTIARY ORGANOPHOSPHINE AT A REACTION TEMPERATURE OF FROM ABOUT 300*F TO ABOUT 500*F IN THE ABSENCE OF CARBON MONOXIDE AND HYDROGEN OR IN THE PRESENCE OF CARBON MONOXIDE BUT WITHOUT HYDROGEN THEREBY ISOMERIZING SAID OLEFINS TO THEIR ALPHA STRUCTURE, MAINTAINING THE REACTION MIXTURE AT SAID TEMPERATURE FOR ABOUT 15 MINUTES THEN HYDROFORMYLATING SAID ALPHA OLEFINS BY CONTACTING SAID REACTION MIXTURE CONTAINING SAID ALPHA OLEFINS WITH SYNTHESIS GAS UNDER A PRESSURE OF FROM ABOUT 1000 TO 3500 PSIF FOR A REACTION TIME OF FROM ABOUT 1 TO 20 HOURS AND
 2. The process of claim 1 wherein the isomerizing reaction pressure ranges from 1500 to 2500 psig.
 3. The process of claim 1 wherein the hydroformylation reaction time ranges from 3 to 10 hours.
 4. The process of claim 1 wherein said olefins are present in a charge of dehydrogenated normal paraffins.
 5. The process of claim 1 wherein said catalyst is cobalt acetate.
 6. The process of claim 1 wherein said ligand is tri-n-butylphosphine.
 7. The process of claim 1 wherein isomerizing is carried out at 340* to 400*F. 